Method of making a covered V-belt having reduced coefficient of friction sides

ABSTRACT

A covered V-belt having reduced coefficient of friction sides and a method for making the same are provided. The outer cover of the belt of this invention comprises a metallic material incorporated with the elastomeric material of the cover, which material is so incorporated either by depositing a thin film of the material onto a finished belt or by mixing a finely divided metallic material into the elastomer.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional patent application of its copendingparent patent application, Ser. No. 147,431 filed May 6, 1980 now U.S.Pat. No. 4,355,994, issued on Oct. 26, 1982.

BACKGROUND OF THE INVENTION

This invention relates to endless power transmission belts.

Endless power transmission belts having a cross-section in the form of atrapezoid, and commonly known as V-belts, are well known and widelyused. V-belts transmit power by wedgingly engaging the complimentarilyshaped groove of a V-pulley. The forced contact between the sides of thepulley groove resists slippage of the belt in the pulley. It isdesirable, however, for the belt to enter and leave the pulley with aslittle resistance as possible. It has been found that a high coefficientof friction between the belt and the pulley results in a comparativelyhigh belt operating tension, while a reduced belt to pulley coefficientof friction results in a reduced belt operating tension.

V-belts are normally characterized by such basic elements as aload-carrying section, generally composed of strength cords embedded inan elastomer, an upper tension section and a lower compression section.An example of a belt of this type is described and illustrated (FIG. 1)in U.S. Pat. No. 3,863,516. The belt may be covered by a fabric envelopeor cover having an elastomer on one or both surfaces thereof, asdescribed and illustrated (FIG. 2) in U.S. Pat. No. 3,863,516. Thefabric covered belt is known in the art as a wrapped, molded V-belt.Where a fabric cover is not used, the resulting belt is commonly knownas a molded or raw-edge belt, depending upon the particularmanufacturing method employed.

The coefficient of friction of raw-edge belts can be reduced byincorporating graphite into the elastomeric material which makes up atleast one of the load-carrying, tension and/or compression sections ofthe belt, as described, for example in U.S. Pat. Nos. 4,024,773 and4,031,768. In the case of fabric covered V-belts polyfluorohydrocarbonresins which have polymer lubricating properties may be incorporatedinto the elastomeric material which is used to impregnate the coverfabric, as described in U.S. Pat. No. 3,661,823.

It is an object of the present invention to provide a novel method forreducing the coefficient of friction between a metal pulley and awrapped, molded V-belt.

It is another object of this invention to provide a novel wrapping,molded V-belt having reduced coefficient of friction pulley-contactingsides.

It is a further object of this invention to provide a method formanufacturing a wrapped, molded V-belt having reduced coefficient offriction sides.

Other objects, aspects and advantages of the present invention will beapparent to those skilled in the art from the following description ofthe invention.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a novelmethod for reducing the coefficient of friction between a metal pulleyand a wrapped, molded V-belt entrained therearound, which comprisesincorporating a metallic material into the cover stock of the belt.

There is also provided a novel wrapped, molded V-belt having a metallicmaterial incorporated into the cover stock of the belt.

There is further provided a method for manufacturing a wrapped, moldedV-belt having reduced coefficient of friction sides.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing,

FIG. 1 is a cross-sectional view illustrating one exemplary embodimentof a wrapped, molded V-belt of this invention;

FIG. 2 is an enlarged fragmentary cross-sectional view taken along lines2--2 of FIG. 1;

FIG. 3 is a block diagram presentation of the method employed to makethe belt of FIG. 1;

FIG. 4 is a cross-sectional view of another exemplary embodiment of awrapped, molded V-belt of this invention;

FIG. 5 is an enlarged fragmentary cross-sectional view taken along lines5--5 of FIG. 4; and

FIG. 6 is a block diagram presentation of the method employed to makethe belt of FIG. 4.

DETAILED DESCRIPTION OF THE DRAWING

Referring now to FIG. 1 of the drawing the belt of this invention isdesignated generally by the reference numeral 10. The belt 10 has atrapezoidal outline when viewed in cross-section and is often referredto as a V-belt.

The belt 10 has a cover 12 which covers its entire peripheral outline.The cover 12 covers a belt body 14 which is made primarily of anelastomeric material and such body includes a tension section 16, aload-carrying section 18 defined in this example by load-carrying meansin the form of a helically-wound load-carrying cord 18, and acompression section 20. Any suitable elastomeric material may beemployed to define the main portion of the belt body. Such material maybe a natural or synthetic rubber or a suitable plastic material.

The cover 12 is preferably made of a woven fabric 22, see FIG. 2, whichmay be a natural or synthetic fabric, such as cotton, rayon, nylon,polyester, aramid, or the like, including blends thereof. The fabric 22has the usual warps 24 and wefts 26 and such fabric is preferably biascut whereby the warps and wefts extend at an angle to the longitudinalaxis of the belt.

The cover 12 has a layer 28 defining one surface thereof and a layer 30defining the opposite surface. The layers 28 and 30 are made preferablyof the same elastomeric material as comprises the major portion of themain body 14 of the belt 10. The layer 30, which defines the outsidesurface of the belt 10 differs from the layer 28 in that the layer 30also comprises a metallic material. The metallic material may be in theform of a finely comminuted material 32 homogeneously dispersed throughthe layer 30, as shown in FIG. 2.

Having described the belt 10, the description will now proceed makingreference to FIG. 3 with a presentation of the method employed to makesuch belt. Referring now to FIG. 3, as shown by block 34, a belt body ismade primarily of any suitable elastomeric material and such belt body,when completed, would have the appearance of the belt body 14illustrated in FIG. 1 within the outer cover 12. Any technique known inthe art may be used to make the belt body.

As shown in the block 36, a cover stock is provided, preferably in theform of a woven cover stock. The cover stock 22 is processed by applyingthe layer 28 of elastomeric material on one surface thereof, asindicated by block 38, the layer 28 being illustrated in FIG. 2. Thelayer 28 is preferably made of the same elastomeric material used todefine the belt body 14 whereby a tenacious bond between the belt bodyand cover 12 is assured. The elastomeric material containing the finelycomminuted metallic material 32 is applied in a layer 30 on the oppositesurface of the cover stock 22 as indicated in the block 40.

The cover stock with the layer 28 of elastomeric material defining onesurface and the layer 30 of elastomeric material containing the metallicmaterial 32 defining its opposite surface is then suitably applied tothe belt body 14 as by a wrapping action, for example, with the surfacelayer 28 in contact with the belt body 14 to define a belt construction,as indicated by the block 42. Any suitable apparatus or technique may beemployed to apply the cover 12 defined by cover stock 22 and layers 28and 30, to the belt body 14.

The belt construction defined after covering the belt body 14 with thecover 12 is the vulcanized or otherwise cured using techniques andapparatus known in the art, as indicated by block 44, to define acompleted belt, illustrated in cross-section in FIG. 1.

Another exemplary embodiment of this invention is illustrated in FIGS.4-6. FIG. 4 illustrates a belt 50 having a cover 52 which covers a beltbody 54 made primarily of elastomeric material. The belt body 54includes a tension section 56, a load-carrying section defined in thisexample by a helically-wound load-carrying cord 58, and a compressionsection 60.

The cover fabric is preferably made of a woven fabric 62, see FIG. 5,which may be a natural or synthetic fabric, such as fabric 22,previously described. The fabric 62 has the usual warps 64 and wefts 66and comprises a layer 68 defining one surface thereof and a layer 70defining the opposite surface. The layers 68 and 70 are made preferablyof the same elastomeric material as comprises the major portion of themain body 54. The belt 50 has a discrete layer 72 of a metallic materialwhich defines the outside surface of the belt.

Having described the belt 50, the description will now proceed makingreference to FIG. 6 with a presentation of the method employed to makethe belt 50. As shown by block 74, a belt body is made primarily of anysuitable elastomeric material. Such belt body, when completed, wouldhave the appearance of the belt body 54 illustrated in FIG. 4 within theouter cover 52. Any technique known in the art may be used to make thebelt body.

As shown by block 76, a cover stock is provided, preferably in the formof a woven cover stock. The cover stock 62 is processed by applyinglayers 68 and 70 of elastomeric material defining the surfaces thereof,as indicated by block 78.

The cover stock with the layers 68 and 70 of elastomeric materialdefining the surfaces thereof is then suitably applied to the belt body54, as indicated by block 80.

The belt construction defined after covering the belt body 54 with thecover 52 is then vulcanized or otherwise cured using techniques andapparatus known in the art, indicated by block 82.

A metallic film is then deposited on the outside surfaces of the curedbelt, as indicated by block 84, using techniques and apparatus known inthe art.

The metallic material 32 may be any suitable metal, metal oxide, metalsulfide or metal alloy. Virtually any metal or metallic material may beused, although common sense should prevail when selecting the metal ormetallic material 32 which is to be incorporated with the elastomericmaterial 30 which defines the outside surface of the belt. The metal ormetallic material 32 should be non-abrasive with regard to the variousmaterials comprising the belt and particularly with regard to the pulleyor sheave that the belt will be operated with. The metal or metallicmaterial 32 should be non-reactive under normal environmentalconditions; that is the material 32 should not react unfavorably withthe elastomer or any of the mixing and processing machinery, or with theatmosphere or environment where the belt is to be used. The metal ormetallic material 32 is preferably softer than the materials commonlyused to make pulleys or sheaves, so as not to wear out the pulley grooveprematurely.

Examples of suitable elemental metals are copper, silver, gold, zinc,cadmium, aluminum, thallium, indium, lead, tin, bismuth, chromium,molybdenum, tungsten, manganese, iron, cobalt and nickel, and mixturesthereof. Examples of suitable alloys are alloys of aluminum with copper,manganese, silicon, iron, magnesium, zinc, tin and lead; alloys ofbismuth with lead, tin, cadmium and mercury and the like, and mixturesthereof; alloys of cobalt with chromium and tungsten; alloys of copperwith aluminum, iron, tin, gold, sliver, lead, manganese, silicon,nickel, zinc, carbon, bismuth, platinum, phosphorous, antimony, cobalt,and the like and mixtures thereof; alloys of iron, nickel and cobaltwith sulfur, manganese, carbon, phosphorous, aluminum, silicon,tungsten, chromium, copper, molybdenum and the like and mixturesthereof. Examples of suitable oxides or sulfides include the oxides andsulfides of the abovenamed elemental metals.

The metal or metallic material 32 is used in finely divided, i.e.comminuted, form. In general the particles 32 range in size from about37 to about 149 micron (U.S. Standard Sieve Series No. 400 to No. 100).The amount of the particles 32 can range from about 1 to about 40 weightpercent of the weight of elastomer.

The metal or metallic material 32 can be mixed into the elastomericmaterial by using technique and apparatus known in the art; and theresulting mixture can be applied to the cover fabric by any techniqueand apparatus known in the art, such as by calendering.

The metallic film 72, previously described, can comprise the elementalmetals, alloys, oxides and sulfides previously described. The film 72may be applied to the belt by sputtering or, preferably, by vacuumdeposition, in accordance with techniques using apparatus well known inthe art.

Reasonable modifications are possible within the scope of thisdisclosure without departing from the scope and spirit thereof.

I claim:
 1. A method for reducing the coefficient of friction between ametal pulley and a wrapped, molded V-belt entrained therearound, whichcomprises incorporating a metallic material into the cover stock of saidbelt by depositing said metallic material on the outside driving surfaceof a finished belt by means selected from sputtering and vacuumdeposition.
 2. A method for reducing the coefficient of friction betweena metal pulley and a wrapped, molded V-belt entrained therearound, whichcomprises incorporating a metallic material by vacuum deposition intothe driving surface of the cover stock of said belt.
 3. In a method formanufacturing a wrapped, molded substantially trapezoidal V-belt havingreduced coefficient of friction non-parallel sides comprising a beltbody having a friction reducing layer of an elastomeric compositionbonded in association with said non-parallel sides, said methodcomprising the steps of:(a) providing a belt body made primarily ofelastomeric material; (b) providing a fabric cover stock for said beltbody; (c) applying a layer of elastomeric material on one surface ofsaid cover stock; (d) applying a layer of elastomeric material on theopposite surface of said cover stock; (e) applying said cover stock withsaid elastomeric layers thereon to said belt body with said one surfacein contact therewith to define a wrapped belt construction; and (f)curing said belt construction to define a completed belt;the improvementwhich comprises the further step of depositing, by sputtering or vacuumdeposition, a thin film of metallic material onto the driving surface ofsaid completed belt.
 4. The method of claim 3 wherein said metallicmaterial is selected from the group consisting of metals, metal oxides,metal sulfides, and alloys of metals.